The present invention relates to a controller and portable programmer therefor for a pneumatically-powered point-to-point industrial robot.
Point-to-point robots are generally the most inexpensive type of industrial robot, typically comprising a body having attached thereto a transfer arm which in turn has mounted at one end thereof a pick-up hand and wrist mount. The body provides vertical lift and rotation motion to the transfer arm and the transfer arm itself is extendable and retractable relative to the body. The wrist mount provides rotary movement to the hand relative to the transfer arm. The hand which may comprise a vacuum cup, pressure grip, or the like, is actuatable for part handling. The extent of each of the various robot movements is defined by mechanical stops which set the limits of travel for each motion. Point-to-point robots do not have the capability of stopping a motion at midstroke. Accordingly, when a particular motion is desired, air pressure is applied to the appropriate cylinder and the particular robot motion commences until the mechanical stop is contacted. By maintaining pressure in the cylinder, the robot remains in the position against the mechanical stop.
In view of the relatively inexpensive nature of pneumatically-powered point-to-point robots, the control systems therefor have been rather rudimentary. For example, air logic control systems are frequently used which are programmed by interconnecting small pieces of plastic tubing on air terminals within the controller. Control is limited to sequencing through a specified series of steps. In addition, some general purpose electronic sequence controllers have been utilized which are less than convenient to program and difficult to reprogram. Moreover, because these electronic sequence controllers are general in nature, their ability to fully optimize the operating efficiency of a robot is significantly compromised.
Accordingly, it is the primary object of the present invention to provide an improved electronic controller for a pneumatically-powered point-to-point robot.
In addition, it is an object of the present invention to provide an electronic controller having a programmable, non-volatile, solid-state memory which eliminates the requirement of creating and maintaining hard copies of the user program for use in re-programming the controller after each shut-down.
Furthermore, it is an object of the present invention to provide an improved portable programmer or "teach control" unit for programming the controller, which is compact and convenient to use, and yet provides the user with a complete array of programming, edit, and test functions.
Additionally, it is an object of the present invention to provide a serial communication link between the controller and the portable programmer which eliminates the requirement of a bulky cable and thus enhances the transportability and convenience of the teach control unit.
The controller of the present invention includes a microprocessor for providing a central processing unit, a read-only memory for storing the main control program, and an output interface for transmitting control signals to the solenoid valves controlling the supply of air to the cylinders used for actuating the robot functions. The controller also features the use of a non-volatile solid-state memory for storing a programmed sequence of encoded robot functions. This memory is non-volatile in the sense that it retains the program when power is removed from the controller, without the requirement of backup batteries. However, the entire program or selected portions thereof (even a single step) may be erased and rewritten without resort to an ultra-violet light source. The controller also includes an input interface for receiving feedback signals from pressure transducers connected to the exhaust side of the cylinders so that positive confirmation of the completion of an operation is received before the controller proceeds to the next program step. The use of positive feedback signals also permits the timing sequence of the robot functions to be optimized, thereby maximizing operating efficiency.
In addition, the teach control unit of the present invention provides the user with a complete array of programming capabilities. The teach control unit contains a display and a keyboard with dedicated keys for robot functions such as GRIP, EXTEND, UP and ROTATE IN, as well as non-robot functions such as OUTPUT for checking a selected output, DELAY for inserting a time delay, and MULTI-ACTION for combining two or more robot functions simultaneously for improving operating efficiency. Also included are various programming and edit keys as well as ten parameter keys. Moreover, the teach control unit includes an interface which provides a serial communication link with the controller which significantly reduces the number of conductors needed to connect the unit to the controller.
Additional objects and advantages of the present invention will become apparent from a reading of the detailed description of the preferred embodiment which makes reference to the following set of drawings in which :